Slack balloon with elastic deformation



May 29, 1928. 1,671,922

L. AVORIO SLACK BALLOON WITH ELASTIC DEFORMATION File F 21, 1927 2 Sheets-Sheet l INVENTOR L war A vo/e/o BY W ATTORNEY 4 May 29, 1928. 1,671,922"

L. AVORIO SLACK BALLOON WITH ELASTIC DEFORMATION Filed Feb. 21, 1927 sheets-sheet 2 A 0/6/ A voe/o ATTORNEY Patented May 29, 1928.

stares PATENT LU'IGI AVORIO, OF ROME, ITALY.

SLACK BALLOOLI WITH ELASTIC DEFORMATION,

Application filed February 21, 1927, Serial No. 170,010, an'din Italy March 13, 1926.

The present inventionrelates to improvements in slack balloons generally, both of the captive and dirigible type, intended to rise at a considerable height, and it has as 5 object a device capable of causing to automatically change the volume of the balloon in dependence of the variations of the internal and external pressure, without causing appreciable variations in the shape of the balloon an inconvenience which, on the con-,

trary, occurs in a rather sensible manner with the self-acting devices hitherto in use;

The devices generally adopted hitherto consist in providing the envelope with elasi tic ropes, whose variation of length in dependence of the pressure exerted by the gas permits to have at the start a balloon of smaller volume completely filled with gas, which is able to reach the height assigned without the necessity of discharging gas and then descend always as completely full as it started with the fabric taut and without folds.

In other words the elastic deformation due to the elongation and to the shortening of the ropes substitutes the Variations of volume of the air bag which just should attain the purpose of keeping the envelope filled during the descent through the admission of air, but which in slack balloons practically does not prove to be efficient owp a dlminution of the efliciency of the empening to the reasons explained hereinafter.

Now while the air bag, provided it works well, would offer the great, advantage of permitting the balloon to keep nearly unaltered its shape, that is to maintain nearly constant the ratio between diameter and length, this is not the case with the elastic deformation device presently in use with 40 which the balloon surely maintains constant the length, but between the diameter of the balloon on the ground and at the greatest height there is a considerable difference which is so much the greater the more. in-' creases the said height. s

This difierence, which actually causes a variation of the shape and sizes of the balloon, greatly afiects the stability of same, particularly in the case of strong winds, owing to the circumstance that the empens nages, which are designed for a given shape of the envelope and which are equally eflicient even in the case of little variations of the shape, are not able to maintain such efIiciency upon the shape having undergone a sensible change. And this is the reason why balloons, particularly those descending from great heights and in which the air bag has been substituted by the elastic deformation, havenever given good results as far as con-' cerns the stability.

Moreover the elastic ropes, to suit the purpose they are intended for, must also be same time they have to permit a strong total orrlce.

gas from V ,70 only sufficiently resist extension, but at the extension so as to allow of the balloon be-q ingv completely stretched especially when it I is the case of balloons having a greatly vary ing volume. Consequently in practice a great difiiculty is experienced in obtaining elastic ropes complying at the same time with both of the said requirements and which, besides that, have the necessary strength to resist heavy tensions, which requires a greater weight of rubber.

In slack balloons or flexible dirigibles with elastic deformation the present invention not only eliminates the main inconvenlence, namely that of the great variation of shape and size of the envelope, which causes nages and consequently of the stability of the balloon, but also the inconvenience concerning the great difficulty in obtaining elastic ropes having the qualities desired and'no excessiveweight, and moreover the working of the deformation device is improved. The principle, upon which the in vention is based, arises from the following considerations:

a. The air bag offers, as already mentioned, the advantage of maintaining nearly unaltered the shape and size of the balloon both on the ground and at a great height, but against this advantage stands a great inconvenience consisting in the fact that during the descent the admission of air is rendered difficult through the inclination of the balloon which produces the inclination loons'descend In flexible dirigibles the in-,

convenience is eliminated because of air being immitted into the air bag by means of ventilators mounted on board, while in slack captive balloons, which have no motors, nor can be provided with them owing to their excessive weight, the inconvenience keeps on to subsist; especially when descending from great heights and with strong winds at the bow and at the lower portion are formed cavities, and the balloons reach the ground not at all taut, thus offering an excessive resistance to the wind.

5. Setting aside the inconveniences indicated hereinbefore, the elastic deformation now in use has the great advantage of preventing the balloon, when descending, from arriving slack, it returns to the ground in the same condition as it started, that is always completely filled, notwithstanding the variations of volume occurred during the ascent. 1

o. If it would be possible to combine the advantages proper of the air bag with those inherent to the elastic deformation, eliminating however the inconveniences of the one andof the other, a balloon would be formed which never undergoes great variations of shape and size and which consequently is stable and, moreover, a balloon would be obtained which during the descent would always be filled and thus be exposed to a little extent only to the action of the wind.

Just in said combination consists the present invention carried into practice by combining the two systems, the combination being, however, performed in such a way as to eliminate the inconveniences of them.

In fact, the air bag balloon, when descending on the ground from a certain height, surely does not receive, as stated, the total quantity of air necessary for maintaining it filled and taut, but it contains nevertheless a certain quantity of air; if the lack of air, that is the difference between the quantity of air necessary and that actually flowed in, is compensated with a corresponding contraction of the fabric of the balloon by meansof elastic ropes, a balloon is thus obtained which meets all the requirements without occasioning any inconvenience.

And in fact the balloon is filled as if it were an' elastic deformation balloon of any type, that is with a minimum quantity of gas, but as soon as it is at the open air, even before ascending, the balloon takes up air in the gas bag, the elastic ropes, which (contrarily to whathappens with a simple elasticdeformation balloon) must be capable of being rapidly elongated, yield and the envelope, owing to the air flowed in, assumes a nearly normal shape and size so that the empennages maintain unaltered their efficiency. Upon the balloon rising, the air, owing to the expansion of the gas during the ascent, is gradually expelled from the air bag, and the elastic ropes extend completely so that at the greatest height allowed the balloon assumes, if it has not already done so previously, its total volumetric capacity.

During the descent the volume of the gas diminishes, into again air and as the quantity of the latter progressively decreases, the elastic ropes get shorter, thus compensating the deficiency of the volume of air and maintaining the balloon always filled, whereby the shape and size are nearly equivalent to the normal ones.

In conclusion in the elastic deformation type, already known, the air chamber is done away with and the elastic ropes are di rectly applied to the gas bag; in the type according to the present invention, on the contrary, the air chamber is preserved entirely or partially, to it is however applied the elastic deformation. 1

i In the annexed drawings, which schematically show the way in which the invention is carried into practice,

Figs. 1 and 2 are respectively a side elevation and a front view of a captive balloon with the elastic deformation according to the invention.

Figs. 8, l and 5 are cross sections of the said balloon in different conditions of inflation.

Fig. 6 is a section of the envelope at a point at which are applied the sheaths for the elastic ropes.

Figs. 7 and 8 show a same portion of the envelope on which the elastic ropes are applied in the stretched and in the shortened condition, respectively.

The said figures refer to a captive balloon, but things do not materially change even for a flexible dirigible in which it is desired to do away with the car ventilator the air chamber enters which, independently of its weight, always gives rise to complications in the construction, in the employment and in the control.

In Fig. 1 which shows the longitudinal view of the balloon, the full .line -aindicates the attachment of the diaphragm of the air chamber and the dotted line -w'- shows the fabric of said diaphragm, which rests completely upon the central portion of the envelope, position which it takes up upon the whole air having been expelled.

Beneath the full line a-, that is beneath the parabola of suspension pis shown the contractile portion Z of the envelope, formed with the elastic ropes fastened to the outer fabric of the envelope.

In Figs. 1 and 2 the balloon is completely filled with gas and consequently without air chamber and with the contractile portion of its wall entirely stretched; Fig. 5 shows the cross section thereof.

The balloon is inflated so as to bringit in:

the condition shows in Fig. 8 with the small est volume, in which case the elastic ropes are inert, and without air chamber. As soon as the balloon rises from the ground the air chamber A through its openings, is filled with air, the elastic ropes, which easily yield, extend and the balloon assumes a nearly normal shape and size, as shown in Fig. 4-.

Upon the balloon keeping on ascending, the volume of the gas increases at the greatest height it completely fills the envelope, expelling all the air and maintaining com pletely stretched the contractile indicated in Fig. 5. 1

During the descent the volume of the gas diminishes again, but at the same time air flows into the air chamber, and since the air,

as explained above, is insufficient to maintain the balloon automatically filled, the elastic ropes compensate its deficiency by lessening, owing to their progressive shortening, the

' air chamber so that the balloon descends as shown in Fig. 4, that is filled and with a nearly normal shape and size, thus maintaining in efficiency the einpennages and conse quently preserving the stability of the balv loon.

As already stated, the elastic ropes must be capable to rapidly extend so that it is unnecessary to use special elastic bands having a great resistance; they may therefore have a minor thickness and consequently a minor weight, thus compensating the increase of weight due to the diaphragm of the air chamber. To this purpose suit very well the usual elastic ropes formed of elastic threads covered with mesh-shaped braided woven material capable to follow the elongation of the threads.

These ropes, which have the woven material on the outer side, by means of a knot or of a tie may easily be fastened to the attachment flaps of the envelope without any danger that, during the use, the rubber may be cut through at the knots or ties, for it is protected by the braided wovenmaterial.

In the known type of deformation balloon the elastic ropes remain detached from the fabric and are fastened only at a few points, such as at the seams of the connection of the gores, so that the fabric corresponding to the width of the gores is not integral with the ropes; when these are inert, the fabric makes moreor less long folds which then are stretched upon the extension of the ropes. However, it is evident that in this way the friction of the fabric upon itself and the stretching of the envelope cannot take place gradually with the extension of the ropes and consequently with the increase of volume.

wall, as I According to the present invention also this inconvenience is obviated by rendering the elastic ropes integral with the fabric, as shown in Figs. 6, 7, 8; the ropes are introduced into a fabric sheath d fastened in a permanent manner to the envelope and within which they may slide; it will be understood that, when the elastic ropes are in the inert state, the fabric of the balloon gets wrinkled forming a plurality of very small folds (Fig. 8) which are then gradually displayed following the extension of the ropes, until they disappear completely as shown in Fig. 7. The sliding motion of the rope within the sheaths is rendered possible through the aforesaid cotton covering which,

III

by obviating the direct contact between the rubber and the woven material, prevents a strong friction thereof.

Lastly the elastic ropes are arranged at convenient intervals, in order to maintain between them well wrinkly the whole fabric of the envelope; in this way that portion of the balloon, at which they are fastened, is entirely provided with folds which, owing to their running in the longitudinal direction of the balloon, do not give rise to an increase of resistance to the wind, as it would happen, on the contrary, if the same folds would run, in the transversal direction.

Claims:

1. In slack captive balloonsor flexible dirigibles, an air bag which is continually and automatically kept filled and under ressure by the infiowing air which reaches its interior under the action of the wind, the air ba having an internal diaphragm free to unfold completely, in combination with means secured to the wall of the bag to effect an elastic contraction of same for the purpose of adapting the volume of the air bag to the volume of the gas, thus practically maintaining unaltered the shape and the size of the envelope.

2. Slack captive balloon or flexible dirigible of the class specified in claim 1, in which the means, which perform the elastic deformation of the external Wall of the air bag, consist of ropes which have inside elastic threads and outside a covering of braided woven material.

3. Slack captive balloon or flexible dirigible of the class specified in claim 1, in which the means, which perform the elastic deformation of the external wall of the air bag, consist of elastic ropes sliding in sheaths fastened upon the fabric of the envelope.

In testimony whereof I have affixe-d my signature this fifth day of February, 1927.

LUIGI AVORIO. 

